This invention relates to a process and apparatus that controls the power delivered to a tool without the use of complicated components. Preciseness and consistency are very important to mass production operations, such as automobile assembly plants. Power tool driving threaded fasteners must be consistent. Industry typically incorporates controlling devices into the power tool. This is very expensive. Also, this approach often has been unsatisfactory because the measuring and controlling are not direct enough. These attempts often lead to large, bulky tools.
For example, in a typical power tool, an input shaft applies torque to a spindle through a series of bevel gears on the shaft and spindle. A transducer measures the torque on the spindle through a torsionally resilient device strain gauges, a gear case, planet gears and ring gears. This circuitous path at best provides a slow response. Measuring and controlling without a transducer would provide a huge cost savings.